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  1. #include <iostream>
  2. #include <unordered_map>
  3. #include <vector>
  4. #include <algorithm>
  5.  
  6. using namespace std;
  7.  
  8. // Function to group elements of the given array based on first occurrence
  9. // of each element
  10. void rearrange(int A[], int n)
  11. {
  12.     // create an empty map to store frequency of each element
  13.     // present in the input array
  14.     unordered_map<int, int> freq;
  15.     vector<int> order;
  16.  
  17.     // traverse the input array and update frequency of each element
  18.     for (int i = 0; i < n; i++) {
  19.         freq[A[i]]++;
  20.  
  21.         if (std::find(order.begin(), order.end(), A[i]) == order.end())
  22.         {
  23.             order.push_back(A[i]);
  24.         }
  25.     }
  26.  
  27.     for (auto & nb : order)
  28.     {
  29.         for (int i = 0;i < freq[nb];i++)
  30.         {
  31.             cout << nb << " ";
  32.         }
  33.     }
  34. }
  35.  
  36. // main function
  37. int main()
  38. {
  39.     int A[] = { 5, 4, 5, 5, 3, 1, 2, 2, 4 };
  40.     int n = sizeof(A)/sizeof(A[0]);
  41.  
  42.     rearrange(A, n);
  43.  
  44.     return 0;
  45. }
  46.  
Success #stdin #stdout 0s 4280KB
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stdin
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Standard input is empty
stdout
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5 5 5 4 4 3 1 2 2
https://ideone.com/iEG2b1
Group elements of an array based on their first occurrence
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
secret

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